Washing machine and method for controlling the same

ABSTRACT

A washing machine having a drying device for generating an air current to dry laundry, includes a drum forming a washing space; a first temperature sensor for sensing the temperature of washing water; a second temperature sensor for sensing the temperature in the drum; and a controller for determining whether or not a washing condition for washing delicate fabrics is satisfied based on the temperature in the drum and the temperature of the washing water, and controlling the drying device, when it is determined that the washing condition is not satisfied, so that a washing operation of the delicate fabrics is performed after the washing condition is satisfied. The washing machine ensures the washing condition suitable to wash the delicate fabrics even when the temperature in the drum is elevated due to the earlier washing operation, and then performs the washing operation of the delicate fabrics, thereby preventing damage to the delicate fabrics due to shrinkage and deformation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.2006-0008524, filed Jan. 26, 2006, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a washing machine for washing delicatefabrics, such as wool and silk, and a method for controlling the same.

2. Description of the Related Art

A drum washing machine vertically moves laundry together with washingwater along the inner circumferential surface of a drum, which ishorizontally disposed, according to the alternate rotation of the drumin the clockwise and counterclockwise directions, thereby washing thelaundry.

Generally, drum washing machines also have a drying function. In thecase that a drum washing machine has the drying function, the drumwashing machine includes an electric heater for heating air, and a ductfor circulating the heated air. Korean Patent Laid-open Publication No.2005-0101788 (dated Oct. 25, 2005) discloses such a drum washingmachine.

Conventionally, a washing machine, which washes laundry using washingwater heated by a heater, has been developed and used.

Korean Patent Laid-open Publication No. 2004-0085507 (dated Oct. 8,2004) discloses a drum washing machine, which washes laundry usingwashing water heated to a high temperature in a short period of time bysupplying steam of a high temperature to the inside of a tub in order toincrease washing capacity.

In a washing machine having at least one out of a function of dryinglaundry using an electric heater, a function of heating washing water soas to increase the temperature of the washing water, and a function ofsupplying steam of a high temperature, although one washing operationhas been finished, the temperature in a drum may be considerablyelevated, and thus, a long cooling time is required until thetemperature in the drum is similar to the temperature of external air.

However, the above conventional washing machine does not consider thetemperature in the drum after the earlier washing operation iscompleted.

As shown in FIG. 1, when the conventional washing machine washes woolenfabrics, a wool course is selected by a user through an input unitprovided on a main body of the washing machine under the condition thatlaundry is placed into a drum (1). The drum is rotated and the weight ofthe laundry is sensed (2), and washing water is supplied to the drum inconsideration of the weight of the laundry (3). Thereafter, the drum isrotated and the laundry in the drum is washed (4).

Although the temperature in the drum is elevated just after the earlierwashing operation has been completed, the conventional washing machinedoes not consider the temperature in the drum. When delicate fabrics,such as wool and silk, are placed into the drum under the condition thatthe temperature in the drum is elevated, and washing water is suppliedfrom the outside of the washing machine to the drum, the delicatefabrics heated by air of a high temperature in the drum contacts thecold washing water. Thereafter, when the delicate fabrics aremechanically washed by the rotation of the drum, the delicate fabricsshrink or deform. Sizes and characteristics of the fabrics are changeddue to the shrinkage or deformation of the delicate fabrics.Accordingly, the conventional washing machine has a limit in washing thedelicate fabrics, such as wool and silk.

As a drying function for smoothing wrinkles of clothing is recentlyapplied to washing machines, the drying function has become morefrequently used. When woolen fabrics are washed after theabove-described drying function is performed, the washing operation ofthe woolen fabrics must be performed after a designated waiting time haselapsed until the temperature in the drum is sufficiently lowered.However, it is difficult for some users to follow this point of thewashing operation. Further, since many users determine a time to performa new washing operation after the earlier washing operation has beencompleted dependent on experience, the washing of the woolen fabrics isoften performed in an unsuitable condition. Accordingly, solutions tothe above problems have been demanded.

SUMMARY OF THE INVENTION

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be apparentfrom the description, or may be learned by practice of the invention.

Therefore, one aspect of the invention is to provide a washing machine,which satisfactorily washes delicate fabrics without the influence of anearlier washing operation, and a method for controlling the same.

Another aspect of the invention is to provide a washing machine, whichperforms a washing operation of delicate fabrics in an appropriatecondition when the temperature in a drum is elevated, and a method forcontrolling the same.

In accordance with one aspect, the present invention provides a washingmachine having a drying device for generating an air current to drylaundry, including: a drum forming a washing space; a first temperaturesensor for sensing the temperature of washing water; a secondtemperature sensor for sensing the temperature in the drum; and acontroller for determining whether or not a washing condition forwashing delicate fabrics is satisfied based on the temperature in thedrum and the temperature of the washing water, and controlling thedrying device when it is determined that the washing condition is notsatisfied, so that a washing operation of the delicate fabrics isperformed after the washing condition is satisfied.

The controller may determine that the washing condition is satisfiedwhen a difference of temperatures between the inside of the drum and thewashing water is less than a predetermined temperature.

The controller may perform a cooling operation for lowering thetemperature in the drum when the temperature in the drum is higher thana reference temperature in the determination of the washing condition.

The drying device may include an air blast fan for generating the aircurrent; a duct for guiding the air current to the inside of the drum; achannel for supplying air, discharged from the inside of the drum, tothe duct; and a cooling water spraying unit for spraying cooling waterto the channel; and the controller may operate the air blast fan andsupply the cooling water through the cooling water spraying unit, whenthe cooling operation is required.

The controller may include a counter for performing the coolingoperation for a predetermined time.

The controller may perform the washing operation of the delicate fabricswhen the washing condition is satisfied by the cooling operation.

The washing machine may further include a heater for heating the washingwater, wherein the controller controls the heater so that the washingwater is heated by the heater, when the washing condition is notsatisfied by the cooling operation.

The controller may perform the washing operation of the delicate fabricswhen the difference of temperatures between the inside of the drum andthe washing water is less than the predetermined temperature.

The delicate fabrics may include wool and silk.

In accordance with another aspect, the present invention provides amethod for controlling a washing machine having a drying device forgenerating an air current to dry laundry, including: selecting a washingcourse for washing delicate fabrics; sensing the temperature in a drumforming a washing space and the temperature of washing water;determining whether or not a washing condition for the delicate fabricsis satisfied; and controlling the drying device when it is determinedthat the washing condition is not satisfied, so that a washing operationof the delicate fabrics is performed after the washing condition issatisfied.

A cooling operation for lowering the temperature in the drum bycirculating the air current generated by the drying device to the insideof the drum may be performed for a predetermined time when thetemperature in the drum is higher than a reference temperature in thedetermination of the washing condition.

The reference temperature may be 35° C.

It may be determined that the washing condition is satisfied when adifference of temperatures between the inside of the drum and thewashing water is less than a predetermined temperature.

The predetermined temperature may be 2° C.

The washing operation of the delicate fabrics may be performed when thewashing condition is satisfied during the cooling operation.

Preliminary washing water may be supplied and heated when the washingcondition is not satisfied after the cooling operation is performed.

The preliminary washing water may be supplied to a heater safetyensuring water level to immerse a heater for heating the washing water.

Whether or not the washing condition is satisfied may be determinedbased on the temperature of the heated washing water and the temperaturein the drum, and the washing operation of the delicate fabrics may beperformed when the washing condition is satisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a flow chart illustrating a method for washing laundry in aconventional wool course;

FIG. 2 is a sectional view of a washing machine in accordance with thepresent invention;

FIG. 3 is a perspective view of a tub of the washing machine inaccordance with the present invention;

FIG. 4 is a block diagram of the washing machine in accordance with thepresent invention;

FIG. 5 is a sectional view of the tub for illustrating the minimum waterlevel and a heater safety ensuring water level; and

FIG. 6 is a flow chart illustrating a method for washing woolen fabricsin accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiment of the presentinvention, an example of which is illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. The embodiment is described below to explain the presentinvention by referring to the annexed drawings.

As shown in FIG. 2, a washing machine in accordance with the presentinvention includes a main body 10 forming the external appearance of thewashing machine, a tub 20 installed in the main body 10 for storingwashing water, and a drum 30 rotatably installed in the tub 20 forcontaining laundry to be washed. A door 11 for opening and closing anopening, which allows a user to place the laundry into the washingmachine, is hinged to the front surface of the main body 10.

First and second water supply pipes 12 a and 12 b for supplying washingwater to the tub 20 and a detergent supply device 13 for supplying adetergent to the tub 20 are installed in the upper portion of the insideof the main body 10. The first water supply pipe 12 a supplies warmwater, and the second water supply pipe 12 b supplies cold water. Firstand second water supply valves 16 and 17 for controlling the watersupply through the first and second water supply pipes 12 a and 12 b arerespectively installed in the first and second water supply pipes 12 aand 12 b. Here, the first water supply valve 16 is a switching valve,and the second water supply valve 17 is a motor-operated three-way valvefor selectively supplying the cold water to the detergent supply device13 and a connection pipe 55.

A heater 22 for heating the washing water and a first temperature sensor23 for sensing the temperature of the washing water are installed on thebottom of the tub 20.

A drain pump motor 14 and a drain pipe 15 for discharging the washingwater contained in the tub 20 to the outside of the main body 10 areinstalled in the lower portion of the inside of the main body 10.

A washing motor 40 for rotating the drum 30 in regular and reversedirections is installed on the external surface of a rear plate 21forming the rear surface of the tub 20, and a rotary shaft 41 fortransmitting the rotary force of the washing motor to the drum 30 isinstalled between the drum 30 and the washing motor 40.

The drum washing machine in accordance with the present inventionfurther includes a drying device 50 for drying the laundry contained inthe drum 30 by supplying warm air to the drum 30. As shown in FIG. 2,the drying device 50 includes an air blast fan 51, a fan motor 51 a, adrying heater 52, a heating duct 53, and a condensation channel 54.

The air blast fan 51 is installed on the tub 20, and supplies drivingforce for circulating air. The heating duct 53 connects an outlet sideof the air blast fan 51 to a front opening the drum 30, and guides anair current generated from the air blast fan 51 to the inside of thedrum 30. The drying heater 52 for heating air so as to effectively drythe laundry is installed in the heating duct 53. The condensationchannel 54 serves to removes moisture from air discharged from the drum30 after the drying of the laundry is completed, and one end of thecondensation channel 54 is connected to the rear surface of the drum 30and the other end of the condensation channel 54 is connected to aninlet side of the air blast fan 51.

As shown in FIG. 3, a channel forming portion 21 a, which is concaved toa designated depth to the rear plate 21, for forming the condensationchannel 54 is formed on the rear plate 21 of the tub 20. A cooling waterspraying unit 56 for spraying cooling water for cooling the air passingthrough the condensation channel 54 is installed in the condensationchannel 54. The cooling water spraying unit 56 is connected to thesecond water supply valve 17 through the connection pipe 55.

Although not shown in FIG. 2, the drum washing machine of the presentinvention further includes a water level sensor 61 installed in the tub20 for sensing the level of the washing water in the tub 20, and asecond temperature sensor 62 for sensing the temperature in the drum 30.

The drum washing machine of the present invention further includes acontroller for controlling the overall operations of the washing machineincluding the washing operation of delicate fabrics. Hereinafter, thecontroller will be described with reference to FIG. 4.

An input unit 60 for inputting user's instructions to the controller 63,the water sensor 61 for sensing the level of the washing water, a firsttemperature sensor 23 for sensing the temperature of the washing water,and the second temperature sensor 62 for sensing the temperature in thedrum 30 are electrically connected to an input side of the controller63.

A valve driving unit 64 for controlling the operations of the first andsecond water supply valves 16 and 17, a heater driving unit 65 forcontrolling the operations of the heater 22 and the drying heater 52,and a motor driving unit 66 for controlling the operations of thewashing motor 40, the drain pump motor 14, and the fan motor 51 a areelectrically connected to an output side of the controller 63.

The controller 63 includes a counter 63-1 for measuring the washingtime.

When a wool course for washing delicate fabrics, for example, wool, isselected, the controller 63 determines whether or not the washingmachine satisfies a washing condition for washing the fabrics withoutshrinkage and damage. When it is determined that the washing conditionis not satisfied, the controller 63 resets a washing condition suitableto wash the fabrics. That is, the controller 63 allows the washingmachine to wash the delicate fabrics only when the washing condition forwashing the woolen fabrics is satisfied.

The controller 63 determines that the washing condition for washingwoolen fabrics is set when a difference of temperatures between theinside of the drum and washing water is not high. At this time, a watersupply operation for sensing the temperature of the washing water isrequired. As shown in FIG. 5, water is supplied to the minimum waterlevel to immerse the first temperature sensor 23.

When the temperature in the drum is excessively high and is not suitableto satisfy the washing condition for the woolen fabrics, the controller63 turns the drying heater 52 off and operates the air blast fan 51.Then, the controller 63 circulates an air current generated from the airblast fan 51 in the drum 30, thereby performing a cooling operation forlowering the temperature in the drum 30.

Thereafter, the controller 63 senses the temperature of the washingwater using the first temperature sensor 23 and the temperature in thedrum 30 using the second temperature sensor 62, and determines whetheror not a difference of the sensed temperatures is in a predeterminedrange. When it is determined that the difference of the sensedtemperatures is not in the predetermined range, the washing water isheated to a high temperature so that a difference of the temperaturesbetween the washing water and the inside of the drum is lowered. Water,which is supplied to heat the washing water, serves as preliminarywashing water. A suitable amount of the preliminary washing water issupplied prior to the supply of main washing water for washing thedelicate fabrics. Here, the preliminary washing water is supplied to aheater safety ensuring water level to immerse the heater 22.

When it is determined that the difference of the sensed temperatures isin the predetermined range, the washing of the woolen fabrics isperformed.

Hereinafter, the operation of the above-described washing machine of thepresent invention will be described.

As shown in FIG. 6, woolen fabrics are placed into the drum 30 of thewashing machine, and a user selects a wool course through the input unit60 provided on the main body 10 (101).

Then, the controller 63 senses the temperature in the drum 30 throughthe second temperature sensor 62 (103), and determines whether or notthe temperature in the drum 30 is higher than a predeterminedtemperature Tr, for example, 35° C. (105). When it is determined thatthe temperature in the drum 30 is not higher than the predeterminedtemperature Tr, the controller 63 recognizes that the washing machinesatisfies a condition suitable to wash the woolen fabrics. Accordingly,the controller 63 rotates the drum 30 so as to sense the weight of thelaundry contained in the drum 30 (107), supplies a designated amount ofwashing water according to the sensed weight of the laundry (109), anddrives the washing motor 40 so as to wash the woolen fabrics (111).

When it is determined that the temperature in the drum 30 is higher thanthe predetermined temperature Tr, the controller 63 drives the fan motor51 a so as to operate the air blast fan 51 under the condition that thedrying heater 52 is turned off, and an air current generated from theair blast fan 51 passes through the heating duct 53 and the drum 20 andis circulated into the condensation channel 54. Here, the controller 63controls the second water supply valve 17 so that cold water passesthrough the connection pipe 55 and is sprayed into the condensationchannel 54 through the cooling water spraying unit 56. Thereby, thecirculating air current is cooled by exchanging heat with the coldwater, thereby being changed into cold air. The temperature in the drum30 is rapidly lowered by the cold air (108). During the above coolingoperation, the counter 63-1 measures the cooling time (110).

Thereafter, the controller 63 supplies cold water to the minimum waterlevel in the tub 20 through the second water supply valve 17 (112). Thecontroller 63 senses the temperature of the washing water through thefirst temperature sensor 23 (114), calculates a difference oftemperatures between the inside of the drum 30 and the washing water(116), and determines whether or not the difference of the temperaturesis less than a predetermined temperature Td (118). When it is determinedthat the difference of the temperatures is less than the predeterminedtemperature Td, the washing of the woolen fabrics is performed by steps107, 109 and 111.

When it is determined that the difference of the temperatures is notless than the predetermined temperature Td, the controller 63 determineswhether or not the measured cooling time exceeds a predetermined time ta(120). When it is determined the measured cooling time does not exceedthe predetermined time ta, step 108 is performed so as to continue thecooling operation.

When it is determined that the measured cooling time exceeds thepredetermined time ta, the controller 63 supplies cold water, serving aspreliminary washing water, to the heater safety ensuring water level inthe tub 20 through the second water supply valve 17 (122). Then, thecontroller 63 heats the washing water using the heater 22 (124), sensesthe temperature of the washing water through the first temperaturesensor 23, calculates a difference of temperatures between the inside ofthe drum 30 and the washing water (128), and determines whether or notthe difference of the temperatures is less than the predeterminedtemperature Td (130). When it is determined that the difference oftemperatures is not less than the predetermined temperature Td, step 124is performed so as to heat the washing water.

When it is determined that the difference of the temperature is lessthan the predetermined temperature Td, the washing of the woolen fabricsis performed by operations 107, 109 and 111.

As apparent from the above description, the present invention provides awashing machine, which performs a cooling operation for lowering thetemperature in a drum so that a difference of temperatures between theinside of the drum and washing water is less than a predeterminedtemperature, when the temperature in the drum is excessively elevateddue to a drying function performed in an earlier washing operation andthe washing machine is not suitable to wash delicate fabrics, such aswool and silk, and supplies preliminary washing water and heats thepreliminary washing water, when the washing condition of the washingmachine after the cooling operation is performed is not satisfied,thereby causing the washing condition to be satisfied. Accordingly, thewashing machine of the present invention performs a washing operationonly when the washing condition for delicate fabrics is satisfied,thereby preventing damage to the delicate fabrics due to shrinkage anddeformation.

Although an embodiment of the invention has been shown and described, itwould be appreciated by those skilled in the art that changes may bemade in this embodiment without departing from the principles and spiritof the invention, the scope of which is defined in the claims and theirequivalents.

1. A washing machine having a drying device for generating an aircurrent to dry laundry, comprising: a drum forming a washing space; afirst temperature sensor for sensing the temperature of washing water; asecond temperature sensor for sensing the temperature in the drum; and acontroller for determining whether or not a washing condition forwashing delicate fabrics is satisfied based on the temperature in thedrum and the temperature of the washing water, and controlling thedrying device when it is determined that the washing condition is notsatisfied, so that a washing operation of the delicate fabrics isperformed after the washing condition is satisfied.
 2. The washingmachine as set forth in claim 1, wherein the controller determines thatthe washing condition is satisfied when a difference of temperaturesbetween the inside of the drum and the washing water is less than apredetermined temperature.
 3. The washing machine as set forth in claim2, wherein the controller performs a cooling operation for lowering thetemperature in the drum when the temperature in the drum is higher thana reference temperature in the determination of the washing condition.4. The washing machine as set forth in claim 3, wherein: the dryingdevice comprises: an air blast fan for generating the air current; aduct for guiding the air current to the inside of the drum; a channelfor supplying air, discharged from the inside of the drum, to the duct;and a cooling water spraying unit for spraying cooling water to thechannel; and the controller operates the air blast fan and supplies thecooling water through the cooling water spraying unit, when the coolingoperation is required.
 5. The washing machine as set forth in claim 3,wherein the controller comprises a counter for performing the coolingoperation for a predetermined time.
 6. The washing machine as set forthin claim 3, wherein the controller performs the washing operation of thedelicate fabrics when the washing condition is satisfied by the coolingoperation.
 7. The washing machine as set forth in claim 3, furthercomprising a heater for heating the washing water, wherein thecontroller controls the heater so that the washing water is heated bythe heater, when the washing condition is not satisfied by the coolingoperation.
 8. The washing machine as set forth in claim 7, wherein thecontroller performs the washing operation of the delicate fabrics whenthe difference of temperatures between the inside of the drum and thewashing water is less the predetermined temperature.
 9. The washingmachine as set forth in claim 1, wherein the delicate fabrics comprisewool and silk.
 10. A method for controlling a washing machine having adrying device for generating an air current to dry laundry, comprising:selecting a washing course for washing delicate fabrics; sensing thetemperature in a drum forming a washing space and the temperature ofwashing water; determining whether or not a washing condition for thedelicate fabrics is satisfied; and controlling the drying device when itis determined that the washing condition is not satisfied, so that awashing operation of the delicate fabrics is performed after the washingcondition is satisfied.
 11. The method as set forth in claim 10, whereina cooling operation for lowering the temperature in the drum bycirculating the air current generated by the drying device to the insideof the drum is performed for a predetermined time when the temperaturein the drum is higher than a reference temperature in the determinationof the washing condition.
 12. The method as set forth in claim 11,wherein the reference temperature is 35° C.
 13. The method as set forthin claim 10, wherein it is determined that the washing condition issatisfied when a difference of temperatures between the inside of thedrum and the washing water is less than a predetermined temperature. 14.The method as set forth in claim 13, wherein the predeterminedtemperature is 2° C.
 15. The method as, set forth in claim 11, whereinthe washing operation of the delicate fabrics is performed when thewashing condition is satisfied during the cooling operation.
 16. Themethod as set forth in claim 15, wherein preliminary washing water issupplied and is heated when the washing condition is not satisfied afterthe cooling operation is performed.
 17. The method as set forth in claim16, wherein the preliminary washing water is supplied to a heater safetyensuring water level to immerse a heater for heating the washing water.18. The method as set forth in claim 16, wherein whether or not thewashing condition is satisfied is determined based on the temperature ofthe heated washing water and the temperature in the drum, and thewashing operation of the delicate fabrics is performed when the washingcondition is satisfied.
 19. A method for washing delicate fabrics in adrum type washing machine including a drying device for generating anair current to dry laundry, the method comprising: selecting a delicatefabric course; sensing a temperature in the drum; circulating cold airin the drum if the temperature in the drum is above a referencetemperature; supplying washing water to the drum to a predeterminedminimum water level; sensing a temperature of the washing water;calculating a difference of temperatures between the temperature in thedrum and the temperature of the washing water; and washing the delicatefabrics if the difference of temperatures between the drum and washingwater is less than a predetermined temperature difference.
 20. Themethod of claim 19, further comprising: supplying warm water to the drumto if the difference of temperatures between the drum and washing wateris more than a predetermined temperature difference; calculating adifference of temperatures between the temperature in the drum and thetemperature of the washing water; and washing the delicate fabrics whenthe difference of temperatures between the drum and washing water isless than a predetermined temperature difference.